[ODE] dWoldStep slowdown

Jon Watte (ODE) hplus-ode at mindcontrol.org
Sat Jun 10 11:04:28 MST 2006

Are you getting debugging output? Debug output is slow. Figure out why 
you're getting it, and correct the cause.
Are you using release or debug versions of ODE? Release is faster.
The system may be reaching near singularity, or may be working with 
denormal numbers. Denormals are really slow on most CPUs.
Do you have lots of contacts? dWorldStep is O(N^3) in the number of 
contacts (constraints). Try using dWorldQuickStep() instead.
Oh, and make sure you're actually deleting your contacts after each step 
(dJointGroupEmpty()). Else they'll just accumulate...

Once you've checked those things, I'd suggest using a profiler (such as 
VTune on Windows or OProfile on Linux) to figure out where it's running 


          / h+

LR wrote:
> Hi,
> I have a problem when geoms mass is not heavy (0,01 Kg) : after a few 
> seconds, dWoldStep slowdown (don't crash) using 750ms for 1 time step ...
> My robot is a spider with 4 legs (2 geoms for each legs, connected 
> with a hinge) and a box for the body (connected with legs with 4 hinges2)
> If every geoms mass is less than ... 200g (0,200), there is a slow 
> down after few seconds, elsewhere all is OK.
> Some one have an idea ?
> Laurent.
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